Nice article:
https://brainbucket.rumbleon.com/mystery-traub-motorcycleSpecs: 1278cc v-twin (in a time when the bigger HD/Indians were 500cc to 700cc) , top speed 85mph, gear box with 3 speeds.
It was all hand built and found in a walled room in 1967 in Chicago.
Apparently it was stolen from Traub's shop in 1916 and the father of the thief was enraged and sent him to fight in the WWI, which he sadly never returned.
It seems that the young rascal decided to hide the bike before leaving for war, which is why it sit hidden for so many decades untouched.